Distance measurement device, distance measurement method, and distance measurement program

ABSTRACT

A distance measurement device includes an imaging optical system, an imaging unit, an emission unit, a derivation unit which performs a distance measurement to derive a distance to a subject based on a timing at which directional light is emitted by the emission unit and a timing at which reflected light is received by a light receiving unit, a shake correction unit which performs shake correction as correction of shake of the subject image caused by variation of an optical axis of the imaging optical system, and a control unit which performs control such that the shake correction unit does not perform shake correction or performs shake correction with a correction amount smaller than a normal correction amount determined in advance in a case of performing the distance measurement and performs shake correction with the normal correction amount in a case of not performing the distance measurement.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 16/438,733, filed Jun. 12, 2019, which is acontinuation application of U.S. patent application Ser. No. 15/333,142,filed Oct. 24, 2016, which is a continuation application ofInternational Application No. PCT/JP2015/056875, filed Mar. 9, 2015, andclaims priority from Japanese Patent Application No. 2014-095556, filedMay 2, 2014, and Japanese Patent Application No. 2014-159806, filed Aug.5, 2014. The disclosures of all of the above applications areincorporated herein by reference in their entireties.

BACKGROUND 1. Technical Field

A technique of the present disclosure relates to a distance measurementdevice, a distance measurement method, and a distance measurementprogram.

2. Related Art

JP2008-96181A discloses a device including time detection means fordetecting the time from the emission of measurement light to thereception of measurement light by light receiving means, shake amountdetection means for detecting a shake amount of a housing duringemission of measurement light when measurement light is emitted fromlight emitting means, and distance determination means for determiningthe distance to an object to be measured based on the time detected bythe time detection means and the shake amount detected by the shakeamount detection means.

JP2002-207163A discloses a distance measurement and imaging devicehaving a function of performing focus adjustment, a distance measurementfunction of measuring a distance to a subject by irradiating the subjectwith a laser beam along an optical axis of a lens and detectingreflected light of the laser beam, and an imaging function of imagingthe subject.

SUMMARY

On the other hand, typically, in a case where a distance measurement isperformed by a distance measurement device, the distance measurementdevice is used in a state of being held by a user. In this state, if aphenomenon in which the vibration of the hand of the user is transmittedto cause the vibration of the distance measurement device, that is,camera shake, occurs, an optical axis of an imaging optical systemincluded in the distance measurement device varies with camera shake. Ina case where the distance measurement device is mounted in a vehicle,the vibration of the vehicle may be transmitted to cause the vibrationof the distance measurement device and the optical axis of the imagingoptical system may vary. Here, the variation of the optical axis meansthat the optical axis is inclined with respect to a reference axis (forexample, an optical axis before camera shake occurs).

In this way, if the optical axis of the imaging optical system varies,image shake or image blur (hereinafter, in a case where there is no needfor distinction, referred to as “shake”) occurs. “Image shake”indicates, for example, a phenomenon in which a subject image isdeviated from a reference position (for example, the position of thesubject image obtained in a state where image shake does not occur) withvariation of the optical axis of the imaging optical system included inthe distance measurement device. “Image blur” indicates, for example, aphenomenon in which an image obtained by imaging is deviated from areference position with the relative movement of the optical axis withrespect to the subject due to camera shake or the like.

In the technique of the related art, in a case of performing correction(shake correction) of shake, the position of the subject image formed onthe imaging unit may vary, and in this case, if a distance measurementis performed, there is a concern that distance measurement accuracy isdegraded.

An embodiment of the invention has been suggested in consideration ofsuch a situation, and provides a distance measurement device, a distancemeasurement method, and a distance measurement program capable ofsuppressing degradation of distance measurement accuracy due to shakecorrection.

In order to attain the above-described object, a distance measurementdevice according to a first aspect of the invention comprises an imagingoptical system which forms a subject image indicating a subject, animaging unit which captures the subject image formed by the imagingoptical system, an emission unit which emits directional light as lighthaving directivity along an optical axis direction of the imagingoptical system, a light receiving unit which receives reflected light ofthe directional light from the subject, a derivation unit which performsa distance measurement to derive a distance to the subject based on atiming at which the directional light is emitted by the emission unitand a timing at which the reflected light is received by the lightreceiving unit, a shake correction unit which performs shake correctionas correction of shake of the subject image caused by variation of theoptical axis of the imaging optical system, and a control unit whichperforms control such that the shake correction unit does not performthe shake correction or performs the shake correction with a correctionamount smaller than a normal correction amount determined in advance ina case of performing the distance measurement and performs the shakecorrection with the normal correction amount in a case of not performingthe distance measurement.

According to a second aspect of the invention, the distance measurementdevice according to the first aspect of the invention may furthercomprise a reception unit which receives an input of an instructionregarding whether or not to perform the distance measurement by theemission unit, the light receiving unit, and the derivation unit, andthe control unit may perform control such that the shake correction unitdoes not perform the shake correction or performs the shake correctionwith a correction amount smaller than a normal correction amountdetermined in advance in a case where an input of an instruction toperform the distance measurement is received by the reception unit andperforms the shake correction with the normal correction amount in acase where an input of an instruction not to perform the distancemeasurement is received by the reception unit.

According to a third aspect of the invention, the distance measurementdevice according to the first or second aspect of the invention mayfurther comprise a detection unit which detects the shake, the shakecorrection unit may calculate a correction amount for correcting theshake based on a detection result of the detection unit, and the controlunit may calculate an irradiation position of the directional lightirradiated from the emission unit based on the calculated correctionamount and may display a marker representing the calculated irradiationposition on a display unit.

According to a fourth aspect of the invention, in the distancemeasurement device according to the third aspect of the invention, thecontrol unit controls the size of the mark representing the irradiationposition based on the calculated correction amount.

According to a fifth aspect of the invention, in the distancemeasurement device according to any one of the first to fourth aspectsof the invention, the derivation unit may perform the derivation of thedistance multiple times and may derive a distance having a highfrequency among the distances obtained by deriving the distance multipletimes as a final distance.

According to a sixth aspect of the invention, the distance measurementdevice according to the fifth aspect of the invention may furthercomprise an execution unit which executes at least one of focusadjustment of the imaging optical system with respect to the subject orexposure adjustment, and in a case where the execution unit executes thefocus adjustment, and in a case of deriving the distance, the derivationunit may determine a distance range for use when determining thefrequency or a time range from the emission of the directional light tothe reception of the directional light based on focusing statespecification information and may derive the final distance within thedetermined distance range or the determined time range.

According to a seventh aspect of the invention, in the distancemeasurement device according to the sixth aspect of the invention, in acase of deriving the distance, the derivation unit may derive the finaldistance with a resolution determined according to a result ofdetermination of the distance range or the time range.

According to an eighth aspect of the invention, in the distancemeasurement device according to any one of the first to seventh aspectsof the invention, the emission unit may be able to adjust the emissionintensity of the directional light and may adjust the emission intensitybased on at least one of focusing state specification information andsubject brightness or exposure state specification information to emitthe directional light.

According to a ninth aspect of the invention, in the distancemeasurement device according to the eighth aspect of the invention, theemission unit may make the emission intensity lower when a focaldistance indicated by the focusing state specification information isshorter.

According to a tenth aspect of the invention, in the distancemeasurement device according to the eighth or ninth aspect of theinvention, the emission unit may make the emission intensity lower whenthe subject brightness is lower and may make the emission intensitylower when the exposure indicated by the exposure state specificationinformation is higher.

According to an eleventh aspect of the invention, in the distancemeasurement device according to any one of the first to tenth aspects ofthe invention, the light receiving unit may be able to adjust lightreceiving sensitivity and may adjust the light receiving sensitivitybased on focusing state specification information to receive thereflected light.

According to a twelfth aspect of the invention, in the distancemeasurement device according to the eleventh aspect of the invention,the light receiving unit may make the light receiving sensitivity lowerwhen a focal distance indicated by the focusing state specificationinformation is shorter.

According to a thirteenth aspect of the invention, the distancemeasurement device according to any one of the first to twelfth aspectsof the invention may further comprise a display unit which displays animage, and the control unit may perform control such that the displayunit displays a motion image captured by the imaging unit and displaysinformation relating to the distance to the subject derived by thederivation unit.

According to a fourteenth aspect of the invention, in the distancemeasurement device according to any one of the first to thirteenthaspects of the invention, a distance measurement by the emission unit,the light receiving unit, and the derivation unit may be performed anumber of times determined in advance according to subject brightness orexposure state specification information. With this, the distancemeasurement device of the fourteenth aspect can obtain a distancemeasurement result, in which the influence of noise of ambient light ismoderated, compared to a case where the light emission frequency ofdirectional light is fixed regardless of subject brightness.

According to a fifteenth aspect of the invention, in the distancemeasurement device according to the fourteenth aspect of the invention,a distance measurement by the emission unit, the light receiving unit,and the derivation unit may be performed a larger number of times whenthe subject brightness is higher or when the exposure indicated by theexposure state specification information is lower. With this, thedistance measurement device according to the fifteenth aspect of theinvention can obtain a distance measurement result, in which theinfluence of noise of ambient light is moderated, compared to a casewhere the light emission frequency of directional light is fixedregardless of high subject brightness.

According to a sixteenth aspect of the invention, the distancemeasurement device according to any one of the first to fifteenthaspects of the invention may further comprise a storage unit whichstores the distance derived by the derivation unit, and storage by thestorage unit may be stopped in a case where the derivation of thedistance by the derivation unit is impossible. With this, the distancemeasurement device according to the sixteenth aspect of the inventioncan prevent storage of incomplete distance data.

According to a seventeenth aspect of the invention, the distancemeasurement device according to the sixteenth aspect of the inventionmay further comprise a storage setting unit which sets whether or not tostop storage by the storage unit in a case where the derivation of thedistance by the derivation unit is impossible. With this, the distancemeasurement device according to the seventeenth aspect of the inventioncan set whether or not to perform storage into the storage unitaccording to a user's intention in a case where the derivation of thedistance is impossible.

According to an eighteenth aspect of the invention, in the distancemeasurement device according to any one of the first to seventeenthaspects of the invention, the derivation unit may derive the distance ina case where there is no focus adjustment error by a focus adjustmentunit performing focus adjustment of the imaging optical system withrespect to the subject and there is no exposure adjustment error by anexposure adjustment unit adjusting exposure in a case where the imagingunit performs imaging. With this, the distance measurement deviceaccording to the eighteenth aspect of the invention can obtain adistance measurement result along with an image subjected to focusingand exposure adjustment.

A distance measurement method according to a nineteenth aspect of theinvention comprises performing a distance measurement to derive adistance to a subject based on a timing at which directional light isemitted by an emission unit emitting directional light as light havingdirectivity along an optical axis direction of an imaging optical systemforming a subject image indicating the subject and a timing at whichreflected light is received by a light receiving unit receiving thereflected light of the directional light from the subject, andperforming control such that a shake correction unit does not performshake correction as correction of shake of the subject image caused byvariation of the optical axis of the imaging optical system or performsthe shake correction with a correction amount smaller than a normalcorrection amount determined in advance in a case of performing thedistance measurement and performs the shake correction with the normalcorrection amount in a case of not performing the distance measurement.

A distance measurement program according to a twentieth aspect of theinvention causes a computer to execute processing including performing adistance measurement to derive a distance to a subject based on a timingat which directional light is emitted by an emission unit emittingdirectional light as light having directivity along an optical axisdirection of an imaging optical system forming a subject imageindicating the subject and a timing at which reflected light is receivedby a light receiving unit receiving the reflected light of thedirectional light from the subject, and performing control such that ashake correction unit does not perform shake correction as correction ofshake of the subject image caused by variation of the optical axis ofthe imaging optical system or performs the shake correction with acorrection amount smaller than a normal correction amount determined inadvance in a case of performing the distance measurement and performsthe shake correction with the normal correction amount in a case of notperforming the distance measurement.

According to an embodiment of the invention, it is possible to suppressdegradation of distance measurement accuracy due to shake correction.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments according to the technique of the presentdisclosure will be described in detail based on the following figures,wherein:

FIG. 1 is a block diagram showing an example of the configuration of amain part of a distance measurement device according to this embodiment;

FIG. 2 is a timing chart showing an example of a timing of a distancemeasurement operation to measure a distance to a subject in the distancemeasurement device according to this embodiment;

FIG. 3 is a timing chart showing an example of a timing from lightemission to light reception in a single measurement in the distancemeasurement device of the first embodiment;

FIG. 4 is a graph showing an example of a histogram of measured valuesin a case where a distance to a subject is set as a horizontal axis anda measurement frequency is set as a vertical axis;

FIG. 5 is a flowchart showing an example of a flow of control processingwhich is executed by a main control unit of the distance measurementdevice according to this embodiment;

FIG. 6 is an example of a timing chart showing the timings of an imagingoperation and a distance measurement operation in the distancemeasurement device according to this embodiment;

FIG. 7 is a flowchart showing an example of distance measurementprocessing which is executed by a distance measurement control unit ofthe distance measurement device according to this embodiment;

FIG. 8 is a flowchart showing another example of a flow of controlprocessing which is executed by the main control unit of the distancemeasurement device according to this embodiment;

FIG. 9 is a flowchart showing another example of a flow of controlprocessing which is executed by the main control unit of the distancemeasurement device according to this embodiment;

FIG. 10A is a diagram illustrating a marker representing an irradiationposition which is displayed on a live view image of a view finder in asuperimposed manner;

FIG. 10B is a conceptual diagram showing an example of a marker whichrepresents an irradiation position displayed on a live view image of aview finder in a superimposed manner and is displayed large;

FIG. 10C is a conceptual diagram showing an example of a marker whichrepresents an irradiation position displayed on a live view image of aview finder in a superimposed manner and is displayed small;

FIG. 11A is a modification example of a histogram obtained in thedistance measurement device according to the embodiment, and is adiagram illustrating an example of deriving a distance to a subjectwithout using a measurement result other than a subject distance rangebased on AF;

FIG. 11B is a modification example of a histogram obtained in thedistance measurement device according to the embodiment, and is adiagram illustrating an example of deriving a distance to a subjectwithout using a measured value of a distance less than a subjectdistance based on AF;

FIG. 11C is a modification example of a histogram obtained in thedistance measurement device according to the embodiment, and is adiagram illustrating an example of deriving a distance to a subjectwithout using a measured value of a distance longer than a subjectdistance based on AF;

FIG. 12 is an explanatory view illustrating adjustment of emissionintensity of a laser beam or light receiving sensitivity of a photodiodebased on an AF result or an AE result;

FIG. 13 is another example of a timing chart representing the timings ofan imaging operation and a distance measurement operation in thedistance measurement device according to this embodiment;

FIG. 14 is a conceptual diagram showing an example of the configurationof a light emission frequency determination table;

FIG. 15 is a flowchart showing an example of a flow of brightnessinformation transmission processing;

FIG. 16 is a flowchart showing an example of a flow of light emissionfrequency determination processing;

FIG. 17 is a conceptual diagram showing another example of theconfiguration of a light emission frequency determination table;

FIG. 18 is a flowchart showing another example of a flow of exposurestate specification information transmission processing; and

FIG. 19 is a flowchart showing another example of a flow of lightemission frequency determination processing.

DETAILED DESCRIPTION

Hereinafter, an example of an embodiment of a distance measurementdevice according to the technique of the present disclosure will bedescribed referring to the accompanying drawings. In this embodiment, a“distance measurement” indicates a measurement of a distance to asubject to be a measurement target.

First, the configuration of the distance measurement device according tothis embodiment will be described. FIG. 1 is a block diagram showing theconfiguration of a main part of a distance measurement device 10according to this embodiment.

The distance measurement device 10 of this embodiment has a function ofperforming a distance measurement and a function of generating acaptured image obtained by imaging a subject. The distance measurementdevice 10 of this embodiment comprises a control unit 20, a lightemitting lens 30, a laser diode 32, a light receiving lens 34, aphotodiode 36, an imaging optical system 40, an imaging element 42, anoperating unit 44, a view finder 46, and a storage unit 48.

The control unit 20 comprises a time counter 22, a distance measurementcontrol unit 24, and a main control unit 26. The time counter 22 has afunction of generating a count signal in each given period determined inadvance according to a signal (for example, a clock pulse) input fromthe main control unit 26 through the distance measurement control unit24.

The distance measurement control unit 24 has a function of performing adistance measurement under the control of the main control unit 26. Thedistance measurement control unit 24 of this embodiment controls thedriving of the laser diode 32 at a timing according to the count signalgenerated by the time counter 22 to perform the distance measurement.The distance measurement control unit 24 functions as a derivation unitaccording to the technique of the present disclosure. Specificimplementation examples of the distance measurement control unit 24include an application specific integrated circuit (ASIC), afield-programmable gate array (FPGA), and the like. The distancemeasurement control unit 24 of this embodiment has a storage unit (notshown). Specific examples of the storage unit in the distancemeasurement control unit 24 include a nonvolatile storage unit, such asa read only memory (ROM), and a volatile storage unit, such as a randomaccess memory (RAM).

The main control unit 26 has a function of controlling the entiredistance measurement device 10. The main control unit 26 of thisembodiment has a function of controlling the imaging optical system 40and the imaging element 42 to image a subject and generating a capturedimage (subject image). The main control unit 26 functions as a controlunit, a shake correction unit, a brightness detection unit, a focusadjustment unit, and an exposure adjustment unit according to thetechnique of the present disclosure. Specific examples of the maincontrol unit 26 include a central processing unit (CPU) and the like.The distance measurement control unit 24 of this embodiment has astorage unit (not shown). Specific examples of the storage unit in thedistance measurement control unit 24 include a nonvolatile storage unit,such as a ROM, and a volatile storage unit, such as a RAM. A controlprogram described below is stored in the ROM in advance.

The main control unit 26 of this embodiment has a function of performingcorrection (shake correction) of shake. The term “shake” used hereinindicates, for example, image shake or image blur accompanied by aphenomenon (camera shake) in which the vibration of the hand of the useris transmitted to cause the vibration of the distance measurement device10, a phenomenon in which the vibration of a vehicle is transmitted tothe distance measurement device 10 mounted in the vehicle (not shown) tocause the vibration of the distance measurement device 10, or the like.The term “image shake” indicates, for example, a phenomenon in which asubject image is deviated from a reference position (for example, theposition of the subject image obtained in a state where camera shakedoes not occur) with variation of the optical axis of the imagingoptical system 40. Furthermore, “image blur” indicates, for example, aphenomenon in which an image obtained by imaging is deviated from areference position with relative movement of the optical axis of theimaging optical system 40 with respect to the subject due to camerashake or the like. The main control unit 26 of this embodiment performsshake correction of a so-called CCD shift system. The main control unit26 performs shake correction based on a detection result of the shakedetection unit 43 by moving the imaging element 42 and adjusting asubject image to be formed on the imaging element 42 in a case whereshake occurs. In this embodiment, the user can operate the operatingunit 44 to select whether or not to perform shake correction. A systemof shake correction is not limited to a CCD shift system, and othergeneral systems (for example, lens shift system shake correction inwhich a vibration-proof lens (not shown) included in the imaging opticalsystem 40 varies according to a detection result of the shake detectionunit 43, electronic correction processing of correcting image blur byprocessing an image signal obtained by imaging, and the like) may beapplied. In this embodiment, “shake correction” includes a meaning ofreduction in shake, in addition to a meaning of elimination of shake.

A program of control processing is not necessarily stored in the maincontrol unit 26 from the beginning. For example, a control program maybe stored in advance in an arbitrary portable storage medium, such as asolid state drive (SSD), a CD-ROM, a DVD, a magneto-optical disk, or anIC card. The distance measurement device 10 may acquire the controlprogram from the portable storage medium storing the control program andmay store the control program in the main control unit 26 or the like.Furthermore, the distance measurement device 10 may acquire the controlprogram from other external devices through the Internet or a local areanetwork (LAN) and may store the control program in the main control unit26 or the like.

The operating unit 44 is a user interface which is operated by the userwhen various instructions are provided to the distance measurementdevice 10. The operating unit 44 includes a release button, a distancemeasurement instruction button, and buttons, keys, or the like (all ofthese are not shown) which are used when the user provides variousinstructions. Various instructions received by the operating unit 44 areoutput to the main control unit 26 as operation signals, and the maincontrol unit 26 executes processing according to the operation signalsinput from the operating unit 44. The operating unit 44 is an example ofa reception unit according to the technique of the present disclosure.

The shake detection unit 43 has a function of detecting shake, andcomprises, for example, a sensor, such as a gyro sensor.

The release button of the operating unit 44 detects a two-stage pressingoperation of an imaging preparation instruction state and an imaginginstruction state. The imaging preparation instruction state indicates,for example, a state of being pressed from a standby position to anintermediate position (half-pressing position), and the imaginginstruction state indicates a state of being pressed to a final pressingposition (fully pressing position) beyond the intermediate position.Hereinafter, “the state of being pressed from the standby position tothe half-pressing position” refers to a “half-pressing state”, and “thestate of being pressed from the standby position to the fully pressingposition” refers to a “fully pressing state”.

In the distance measurement device 10 according to this embodiment, amanual focus mode and an auto-focus mode are selectively set accordingto a user's instruction. In the auto-focus mode, adjustment of imagingconditions is performed by bringing the release button of the operatingunit 44 into the half-pressing state, and then, exposure (imaging) isperformed by successively bringing the release button into the fullypressing state. That is, if the release button of the operating unit 44is brought into the half-pressing state, an automatic exposure (AE)function is operated to perform exposure adjustment, and an auto-focus(AF) function is operated to perform focusing control, and if therelease button is brought into the fully pressing state, imaging isperformed.

In this embodiment, the main control unit 26 transmits exposure statespecification information for specifying an exposure state at thepresent time as a result of AE to the distance measurement control unit24. The main control unit 26 transmits focusing state specificationinformation for specifying a focusing state at the present time as aresult of AF to the distance measurement control unit 24. Examples ofthe exposure state specification information include an F-number and ashutter speed derived from a so-called AE evaluation value uniquelydetermined according to subject brightness. Other examples of theexposure state specification information include an AE evaluation value.Examples of the focusing state specification information include thesubject distance obtained by AF.

The storage unit 48 primarily stores image data obtained by imaging, anda nonvolatile memory is used therefor. Specific examples of the storageunit 48 include a flash memory or a hard disk drive (HDD).

The view finder 46 has a function of displaying images, characterinformation, and the like. The view finder 46 of this embodiment is anelectronic view finder (hereinafter, referred to as “EVF”), and is usedfor displaying a live view image (through-image) as an example of acontinuous-frame image obtained by imaging in continuous frames duringimaging. The view finder 46 is also used for displaying a still image asan image of a single-frame image obtained by imaging in a single framein a case where an instruction to capture a still image is provided. Inaddition, the view finder 46 is also used for displaying a reproducedimage in a playback mode or displaying a menu screen or the like.

The imaging optical system 40 comprises an imaging lens including afocus lens, a motor, a slide mechanism, and a shutter (all of these arenot shown). The slide mechanism moves the focus lens along the opticalaxis direction (not shown) of the imaging optical system 40. The focuslens is attached so as to be slidable along the optical axis directionof the slide mechanism. The motor is connected to the slide mechanism,and the slide mechanism receives power of the motor and slides the focuslens along the optical axis direction. The motor is connected to themain control unit 26 of the control unit 20, and is controlled anddriven according to a command from the main control unit 26. In thedistance measurement device 10 of this embodiment, as a specific exampleof the motor, a stepping motor is applied. Accordingly, the motor isoperated in synchronization with pulse power in response to a commandfrom the main control unit 26.

In the distance measurement device 10 according to this embodiment, inthe auto-focus mode, the main control unit 26 performs focusing controlby driving and controlling the motor of the imaging optical system 40such that a contrast value of an image obtained by imaging with theimaging element 42 becomes the maximum. Furthermore, in the auto-focusmode, the main control unit 26 calculates AE information which is aphysical quantity indicating brightness of an image obtained by imaging.The main control unit 26 derives a shutter speed and an F-number(aperture value) according to the brightness of the image indicated bythe AE information when the release button of the operating unit 44 isbrought into the half-pressing state. The main control unit 26 performsexposure adjustment by controlling respective related units such thatthe derived shutter speed and F-number are obtained.

The imaging element 42 is an imaging element comprising color filters(not shown), and functions as an imaging unit according to the techniqueof the present disclosure. In this embodiment, as an example of theimaging element 42, a CMOS type image sensor is used. The imagingelement 42 is not limited to a CMOS type image sensor, and may by, forexample, a CCD image sensor. The color filters include a G filtercorresponding green (G) most contributing to obtaining a brightnesssignal, an R filter corresponding to red (R), and a B filtercorresponding to blue (B). Any filter of “R”, “G”, and “B” included inthe color filters is allocated to each of the pixels (not shown) of theimaging element 42.

In a case of imaging a subject, image light indicating the subject isformed on the light receiving surface of the imaging element 42 throughthe imaging optical system 40. The imaging element 42 has a plurality ofpixels (not shown) arranged in a matrix in a horizontal direction and avertical direction, and signal charges according to image light arestored in the pixels of the imaging element 42. The signal chargesstored in the pixels of the imaging element 42 are sequentially read asdigital signals according to the signal charges (voltages) under thecontrol of the main control unit 26. In the distance measurement device10 of this embodiment, the signal charges are sequentially read in unitsof pixels for each horizontal direction, that is, for each pixel row. Ina period from when the electric charges are read from the pixels of onepixel row until the electric charges are read from the pixels of thenext pixel row, a period (hereinafter, referred to as a “horizontalblanking period”) during which the signal charges are not read isgenerated.

The imaging element 42 has a so-called electronic shutter function, andoperates the electronic shutter function to control an electric chargestorage time (shutter speed) of each photosensor at a timing under thecontrol of the main control unit 26.

The imaging element 42 outputs the digital signals indicating the pixelvalues of the captured image from the respective pixels. The capturedimage output from the respective pixels is a chromatic image, and is,for example, a color image having the same color arrangement as thepixel arrangement. The captured image (frames) output from the imagingelement 42 is temporarily stored (overwritten and saved) in the storageunit of the main control unit 26 or a RAW image storage area (not shown)of the storage unit 48 determined in advance through the main controlunit 26.

The main control unit 26 subjects the frames to various kinds of imageprocessing. The main control unit 26 has a white balance (WB) gain unit,a gamma correction unit, and a synchronization processing unit (all ofthese are not shown), and sequentially performs signal processing forthe original digital signals (RAW images) temporarily stored in the maincontrol unit 26 or the like in each processing unit. That is, the WBgain unit executes white balance (WB) adjustment by adjusting the gainof each of R, G and B signals. The gamma correction unit performs gammacorrection of each of the R, and B signals subjected to the WBadjustment in the WB gain unit. The synchronization processing unitperforms color interpolation processing corresponding to the arrangementof the color filters of the imaging element 42 and generates thesynchronized R, and B signals. Each time the RAW image for one screen isacquired by the imaging element 42, the main control unit 26 performsimage processing for the RAW image in parallel.

The main control unit 26 outputs image data of the generated capturedimage for recording to an encoder (not shown), which converts an inputsignal to a signal in a different format. The R, and B signals processedby the main control unit 26 are converted (encoded) to signals forrecording by the encoder, and the signals for recording are recorded inthe storage unit 48. The captured image for display processed by themain control unit 26 is output to the view finder 46. Hereinafter, forconvenience of description, in a case where there is no need fordistinction between the “captured image for recording” and the “capturedimage for display”, the expression “for recording” and the expression“for display” are omitted and the captured image for recording and thecaptured image for display are referred to as “captured images”.

The main control unit 26 of this embodiment displays a live view imageon the view finder 46 by performing control for continuously displayingthe captured images for display as a motion image.

The light emitting lens 30 and the laser diode 32 function as an exampleof an emission unit according to the technique of the presentdisclosure. The laser diode 32 is driven based on an instruction fromthe distance measurement control unit 24 and has a function of emittinga laser beam toward the subject to be a measurement target through thelight emitting lens 30 in the optical axis direction of the imagingoptical system 40. Specific examples of the light emitting lens 30 ofthis embodiment include an objective lens or the like. The laser beamemitted from the laser diode 32 is an example of directional lightaccording to the technique of the present disclosure.

The light receiving lens 34 and the photodiode 36 function as an exampleof a light receiving unit according to the technique of the presentdisclosure. The photodiode 36 has a function of receiving the laser beamemitted from the laser diode 32 and reflected from the subject throughthe light receiving lens 34 and outputting an electrical signalaccording to the amount of received light to the distance measurementcontrol unit 24.

If the user provides an instruction to measure (distance measurement) adistance to a subject using the distance measurement instruction buttonor the like of the operating unit 44, the main control unit 26 instructsthe distance measurement control unit 24 to perform a distancemeasurement. Specifically, in this embodiment, the main control unit 26instructs the distance measurement control unit 24 to perform a distancemeasurement by transmitting a distance measurement instruction signal tothe distance measurement control unit 24. In a case of performing ameasurement of a distance to a subject and imaging of the subject inparallel, the main control unit 26 transmits a synchronization signalfor synchronizing a distance measurement operation and an imagingoperation to the distance measurement control unit 24.

If the synchronization signal and the distance measurement instructionsignal are received, the distance measurement control unit 24 controlsthe light emission of the laser diode 32 at a timing according to thecount signal of the time counter 22 and controls a timing of emitting alaser beam toward the subject. The distance measurement control unit 24samples the electric signal according to the amount of received lightoutput from the photodiode 36 at the timing according to the countsignal of the time counter 22.

The distance measurement control unit 24 derives the distance to thesubject based on the light emission timing at which the laser diode 32emits a laser beam and the light reception timing at which thephotodiode 36 receives the laser beam, and outputs distance datarepresenting the derived distance to the main control unit 26. The maincontrol unit 26 displays information relating to the distance to thesubject on the view finder 46 based on distance data. The main controlunit 26 stores distance data in the storage unit 48.

The measurement of the distance to the subject by the distancemeasurement control unit 24 will be described in more detail. FIG. 2 isa timing chart showing an example of a timing of the distancemeasurement operation in the measurement of the distance to the subjectin the distance measurement device 10.

In the distance measurement device 10 of this embodiment, a singledistance measurement (measurement) sequence includes a voltageadjustment period, an actual measurement period, and a pause period. Thevoltage adjustment period refers to a period during which a drivevoltage of the laser diode 32 and the photodiode 36 is adjusted to anappropriate voltage value. As a specific example, in the distancemeasurement device 10 of this embodiment, as shown in FIG. 2, thevoltage adjustment period is set to several 100 msec (milliseconds).

The actual measurement period refers to a period in which the distanceto the subject is actually measured. In the distance measurement device10 of this embodiment, as a specific example, as shown in FIG. 2, thedistance to the subject is measured by repeating an operation to emit alaser beam and to receive the laser beam reflected from the subjectseveral 100 times and measuring the elapsed time from light emission tolight reception. That is, in the distance measurement device 10 of thisembodiment, in the single measurement sequence, the measurement of thedistance to the subject is performed several 100 times.

FIG. 3 is an example of a timing chart showing a timing from lightemission to light reception in a single measurement. In a case ofperforming a measurement, the distance measurement control unit 24outputs a laser trigger for causing the laser diode 32 to emit lightaccording to the count signal of the time counter 22 to the laser diode32. The laser diode 32 emits light according to the laser trigger. Inthe distance measurement device 10 of this embodiment, as a specificexample, the light emission time of the laser diode 32 is set to several10 nsec (nanoseconds). The emitted laser beam is emitted toward thesubject through the light emitting lens 30 in the optical axis directionof the imaging optical system 40. The laser beam emitted from thedistance measurement device 10 is reflected from the subject and reachesthe distance measurement device 10. The photodiode 36 of the distancemeasurement device 10 receives the reflected laser beam through thelight receiving lens 34.

In the distance measurement device 10 of this embodiment, as a specificexample, the distance measurement device performs a distance measurementfor a subject within 1 km from the distance measurement device 10. Thetime until the laser beam emitted from the laser diode 32 toward thesubject 1 km ahead through the light emitting lens 30 is returned(received) becomes 1 km×2/light speed=several μsec (microseconds).Accordingly, in order to measure the distance to the subject 1 km ahead,as shown in FIG. 2, the time of at least several μsec is required.

In the distance measurement device 10 of this embodiment, thereciprocation time or the like of the laser beam is considered, and as aspecific example, a single actual measurement time is set to severalmsec as shown in FIG. 2. Since the reciprocation time of the laser beamis different depending on the distance to the subject, the actualmeasurement time for each time may be different depending on thedistance assumed by the distance measurement device 10.

In the distance measurement device 10, the distance measurement controlunit 24 derives the distance to the subject based on measured valuesobtained by performing a measurement several 100 times as describedabove. In the distance measurement control unit 24 of this embodiment,as a specific example, a histogram of measured values for several 100times is analyzed to derive the distance to the subject. FIG. 4 is agraph showing an example of a histogram of measured values in a casewhere the distance to the subject is set as a horizontal axis and themeasurement frequency is set as a vertical axis. The distancemeasurement control unit 24 derives the distance to the subjectcorresponding to a maximum value of the measurement frequency in theabove-described histogram as a measurement result and outputs distancedata indicating the derived measurement result to the main control unit26. A histogram may be generated based on the reciprocation time (theelapsed time from light emission to light reception) of the laser beamor ½ of the reciprocation time of the laser beam, or the like, insteadof the distance to the subject.

The pause period refers to a period for pausing the driving of the laserdiode 32 and the photodiode 36. In the distance measurement device 10 ofthis embodiment, as a specific example, as shown in FIG. 2, the pauseperiod is set to several 100 msec.

In the distance measurement device 10 of this embodiment, the singlemeasurement time is set to several 100 msec.

In a case of not performing imaging, the main control unit 26 of thedistance measurement device 10 of this embodiment displays a live viewimage on the view finder 46 as described above. The main control unit 26performs the display of the live view image by displaying the capturedimages captured in several 10 fps (several 10 msec/image) on the viewfinder 46 as a motion image. For this reason, during the singlemeasurement period, live view images for measurement period/fps aredisplayed on the view finder 46.

Next, the imaging operation and the distance measurement operation in acase where the imaging operation and the distance measurement operationin the distance measurement device 10 of this embodiment aresynchronized will be described. Hereinafter, as a specific example, animaging operation and a distance measurement operation in a case wherean imaging operation to capture a still image and a distance measurementoperation are synchronized will be described.

First, control processing which is executed by the main control unit 26will be described. FIG. 5 is a flowchart showing an example of a flow ofcontrol processing which is executed by the main control unit 26 of thedistance measurement device 10 of this embodiment. FIG. 6 shows anexample of a timing chart showing the timings of the imaging operationand the distance measurement operation. The flowchart shown in FIG. 5 isexecuted if power is supplied to the distance measurement device 10.

First, in Step 100, the main control unit 26 starts a live viewoperation. As described above, the main control unit 26 displays thelive view image on the view finder 46 by performing control forcontinuously displaying the captured images captured by the imagingoptical system 40 and the imaging element 42 as a motion image.

Next, in Step 102, the main control unit 26 determines whether or not toperform a distance measurement.

In the distance measurement device 10 of this embodiment, as describedabove, shake correction of a so-called CCD shift system is performed bythe main control unit 26. For this reason, since the imaging element 42is moved, the position (image forming position) of the subject image isalso moved. In this way, if a distance measurement is performed in astate where the position of the subject image is moved, a distancemeasurement location (a place where a laser beam is reflected) may bedifferent from the central position of the captured image. In this case,there is a concern that distance measurement accuracy is degraded. Forthis reason, in the distance measurement device 10 of this embodiment,in a case where the distance measurement operation and the imagingoperation are performed in parallel, the main control unit 26 performscontrol such that shake correction is not performed.

Whether or not to perform a distance measurement is determined accordingto whether or not the user instructs the distance measurement throughthe operating unit 44, or the like. In a case of not performing thedistance measurement, the process progresses to Step 136. In a case ofnot performing the distance measurement, the above-described problemdoes not occur. For this reason, the main control unit 26 performs shakecorrection. With this, the main control unit 26 performs the imaging ofthe subject while performing shake correction. After this step, theprocess progresses to Step 138, and the imaging of the subject isperformed by the main control unit 26. In the imaging of this case,since the distance measurement is not performed, a normal imagingoperation (normal imaging) may be performed. Specifically, thoughdetails will be described below, the main control unit 26 performs theprocessing of Steps 106 to 112 and Steps 116 to 120, and may store thecaptured image (image data indicating the captured image) in the storageunit 48.

In a case of performing the distance measurement, that is, in a case ofperforming both of the imaging of the subject and the distancemeasurement of the distance to the subject, the process progresses toStep 104. In Step 104, shake correction is not performed. With this, themain control unit 26 performs the imaging of the subject withoutperforming shake correction.

Next, in Step 106, the main control unit 26 determines whether or notthe release button of the operating unit 44 is half-pressed. In a casewhere the release button is not half-pressed, for example, in a casewhere the release button is not pressed at all, or the like, the processprogresses to Step 140. In a case where the release button ishalf-pressed, the process progresses to Step 108.

In Step 108, the main control unit 26 controls the imaging opticalsystem 40 and performs AE and AF as described above. In the distancemeasurement device 10, exposure adjustment is performed by performingAE, focusing control is performed by performing AF, and image lightindicating the subject is formed on the light receiving surface of theimaging element 42 in a focused state.

Next, in Step 110, the main control unit 26 determines whether or notthe release button of the operating unit 44 is fully pressed. In a casewhere the release button is not fully pressed, the process progresses toStep 110. In Step 110, the main control unit 26 determines whether ornot a pressing operation to the release button of the operating unit 44is released. In a case where pressing is not released, the processreturns to Step 108, and this processing is repeated. In a case wherepressing is released, the process progresses to Step 140.

In a case where the release button is fully pressed, the processprogresses from Step 110 to Step 114. In Step 114, the main control unit26 transmits the synchronization signal to the distance measurementcontrol unit 24. In this way, in the distance measurement device 10 ofthis embodiment, in order to synchronize the imaging operation by themain control unit 26 with the distance measurement operation by thedistance measurement control unit 24, prior to the start of the imaging(actual exposure to the imaging element 42), the synchronization signalis transmitted from the main control unit 26 to the distance measurementcontrol unit 24. Though details will be described below, in the distancemeasurement control unit 24, if the synchronization signal is received,the distance measurement operation (the measurement of the distance tothe subject) starts.

Next, in Step 116, the main control unit 26 starts the actual exposure(imaging). With the start of the actual exposure, the pixels of theimaging element 42 are irradiated with light (image light is formed onthe light receiving surface of the imaging element 42), and signalcharges according to irradiated light are stored in the respectivepixels.

Next, in Step 118, the main control unit 26 detects whether or not theactual exposure ends. The process is in a standby state until the actualexposure ends, and in a case where the actual exposure ends, the processprogresses to Step 120. A determination method of whether or not theactual exposure ends is not limited, and as a specific example, adetermination method based on determination of whether or not an actualexposure time determined under various conditions has elapsed is used.

In Step 120, the main control unit 26 starts the reading of the signalcharges stored in the respective pixels of the imaging element 42. Next,in Step 122, the main control unit 26 outputs a reading start signalindicating the start of the reading to the distance measurement controlunit 24.

The signal charges read from the respective pixels are transmitted tothe main control unit 26 as electrical signals (image signals), whichare digital signals according to the signal charges.

Next, in Step 124, the main control unit 26 determines whether or not itis the horizontal blanking period. As described above, in a case ofreading the signal charges from the pixels of the imaging element 42,since the signal charges are read in units of pixels for each pixel row,the horizontal blanking period during which the reading of the signalcharges are not performed is generated between the pixel rows. The maincontrol unit 26 determines whether or not it is the horizontal blankingperiod, and in a case where it is not the horizontal blanking period,for example, while the signal charges are read from the pixels of onepixel row, the process progresses to Step 128. In a case of thehorizontal blanking period, the process progresses to Step 126. In Step126, the main control unit 26 transmits a light emission instructionsignal to the distance measurement control unit 24. Though details willbe described below, if the light emission instruction signal isreceived, the distance measurement control unit 24 causes the laserdiode 32 to emit light based on the received light emission instructionsignal.

Next, in Step 128, the main control unit 26 determines whether or not toend the reading. In a case where the signal charges are not yet readfrom all pixels of the imaging element 42, the process returns to Step124, and this processing is repeated. In a case where the signal chargesare read from all pixels of the imaging element 42, the processprogresses to Step 130.

In Step 130, the main control unit 26 transmits a reading end signalindicating the end of the reading to the distance measurement controlunit 24.

Next, in Step 132, the main control unit 26 determines whether or notdistance data is received. Though details will be described below, ifthe distance to the subject is measured (distance measurement), thedistance measurement control unit 24 transmits distance data indicatinga measurement result to the main control unit 26. The process is in astandby state until distance data transmitted from the distancemeasurement control unit 24 is received, and in a case where distancedata is received, the process progresses to Step 134.

In Step 134, the main control unit 26 displays information relating tothe distance to the subject on the view finder 46 based on receiveddistance data. The main control unit 26 stores received distance data inthe storage unit 48 in correlation with the captured image. With thisstep, the captured image (image data indicating the captured image)obtained by imaging the subject and the distance (distance data) to thesubject are stored in the storage unit 48 in a state of being correlatedwith each other.

Next, in Step 140, the main control unit 26 determines whether or not apower switch (not shown) is turned off. In a case where the switch isnot turned off, the process returns to Step 106, and this processing isrepeated. In a case where the power switch is turned off, the processprogresses to Step 142.

In Step 142, the main control unit 26 stops the live view operation, andthen, ends this processing. The main control unit 26 turns off the powersupply of the distance measurement device 10.

Next, distance measurement processing which is executed by the distancemeasurement control unit 24 will be described. FIG. 7 is a flowchartshowing an example of a flow of distance measurement processing which isexecuted by the distance measurement control unit 24 of the distancemeasurement device 10 of this embodiment.

The flowchart shown in FIG. 7 is executed if power is supplied to thedistance measurement device 10.

First, in Step 200, the distance measurement control unit 24 determineswhether or not the synchronization signal is received. Specifically, thedistance measurement control unit 24 determines whether or not thesynchronization signal transmitted from the main control unit 26 in Step114 of the control processing in the main control unit 26 describedabove is received. The process is in a standby state until thesynchronization signal is received, and if the synchronization signal isreceived, the process progresses to Step 202.

In Step 202, the distance measurement control unit 24 transits to thevoltage adjustment period shown in FIG. 6 and performs voltageadjustment of the drive voltage of the laser diode 32 and the photodiode36.

Next, in Step 204, the distance measurement control unit 24 determineswhether or not the voltage adjustment ends. In this embodiment, asdescribed above and as shown in FIG. 6, the voltage adjustment period isset to several 100 msec. For this reason, the distance measurementcontrol unit 24 determines that the voltage adjustment ends in a casewhere several 100 msec have elapsed after the transition to the voltageadjustment period. Accordingly, the distance measurement control unit 24determines that the voltage adjustment does not end and is in a standbystate until several 100 msec have elapsed after the transition to thevoltage adjustment period, and in a case where several 100 msec haveelapsed, determines that the voltage adjustment ends and progresses toStep 206.

In Step 206, the distance measurement control unit 24 transits to theactual measurement period and starts to measure the distance to thesubject.

Next, in Step 208, the distance measurement control unit 24 determineswhether or not the reading start signal is received. Specifically, thedistance measurement control unit 24 determines whether or not thereading start signal transmitted from the main control unit 26 in Step122 of the control processing in the main control unit 26 describedabove is received.

For this reason, the distance measurement control unit 24 of thedistance measurement device 10 of this embodiment performs control suchthat, in a reading period, the laser diode 32 emits light in theabove-described horizontal blanking period which is a period duringwhich the charge signals are not read from the pixels. That is, thedistance measurement control unit 24 performs control such that, in thereading period, the laser diode 32 emits light in synchronization withthe imaging operation.

As described above, in a period out of the reading period, sincesuperimposition of noise due to variation in voltage does not cause aproblem, the laser diode 32 may not emit light in synchronization withthe imaging operation, and as described above, the laser diode 32 mayemit light every several msec according to each measurement.Hereinafter, control by the distance measurement control unit 24 in aperiod out of the reading period is referred to as “normal control”.

For this reason, in the distance measurement control unit 24 of thedistance measurement device 10 of this embodiment, control in themeasurement of the distance to the subject is different between thereading period and a period out of the reading period.

In Step 208, since the distance measurement control unit 24 performs thenormal control in a case where the reading start signal is not received,the process progresses to Step 216. In a case where the distancemeasurement control unit 24 receives the reading start signal, theprocess progresses to Step 210.

In Step 210, the distance measurement control unit 24 determines whetheror not the reading end signal is received.

Specifically, the distance measurement control unit 24 determineswhether or not the reading end signal transmitted from the main controlunit 26 in Step 130 of the control processing in the main control unit26 described above is received.

Since the distance measurement control unit 24 performs the normalcontrol in a subsequent period in a case where the reading end signal isreceived, the process progresses to Step 216. In a case where thedistance measurement control unit 24 does not receive the reading endsignal, the process progresses to Step 212.

In Step 212, the distance measurement control unit 24 determines whetheror not the light emission instruction signal is received. Specifically,the distance measurement control unit 24 determines whether or not thelight emission instruction signal transmitted from the main control unit26 in Step 126 of the control processing in the main control unit 26described above is received.

In a case where the distance measurement control unit 24 does notreceive the light emission instruction signal, that is, in a case whereit is in the reading period and it is not yet in the horizontal blankingperiod, the process is in the standby state. In a case where thedistance measurement control unit 24 receives the light emissioninstruction signal, the process progresses to Step 214. In Step S214, itis determined whether or not the measurement is being performed. In thedistance measurement device 10 of this embodiment, the interval (thereading time of the charge signals from the pixels of one pixel row)between the horizontal blanking periods is shorter than the singlemeasurement time (in the specific example described above, severalmsec). For this reason, before the measurement ends, the next horizontalblanking period may be reached, and the light emission instructionsignal may be transmitted from the main control unit 26 to the distancemeasurement control unit 24. In the distance measurement control unit 24of this embodiment, in this way, in a case where the light emissioninstruction signal is received during the measurement, the receivedlight emission instruction signal is neglected, whereby the laser diode32 does not emit light. For this reason, in a case where the measurementis being performed, the process progresses to Step 226. In a case wherethe measurement is not being performed, the process progresses to Step216.

In Step 216, the distance measurement control unit 24 causes the laserdiode 32 to emit light. Next, in Step 218, the distance measurementcontrol unit 24 determines whether or not a predetermined time haselapsed. Specifically, as described above, since the single measurementtime is set to several msec, the distance measurement control unit 24determines whether or not several msec have elapsed. In a case where thepredetermined time (in this embodiment, several msec which are thesingle measurement time) has not elapsed, the process is in the standbystate, and in a case where the predetermined time has elapsed, theprocess progresses to Step 220.

The laser diode 32 emits light through the processing of Step 216,whereby the laser beam is emitted toward the subject through the lightemitting lens 30. The laser beam reflected from the subject is receivedby the photodiode 36 through the light receiving lens 34 until thepredetermined time elapses. The distance measurement control unit 24acquires the elapsed time from light emission to light reception in acase where the laser beam is received by the photodiode 36 and storesthe elapsed time in the storage unit (for example, the RAM or the likein the distance measurement control unit 24).

For example, in a case where the subject moves, or the like, the elapsedtime from light emission to light reception of the laser beam exceedsseveral msec which are the actual measurement time per measurement, andthe laser beam may not be returned (reflected light may not bereceived). In this case, a measurement error occurs. In a case where ameasurement error occurs, the distance measurement control unit 24stores the effect in the storage unit (for example, the RAM or the likein the distance measurement control unit 24), and the occurrence of themeasurement error may be displayed on the view finder 46 or the likeaccording to the frequency of the occurrence of the measurement error,for example, if the frequency is not negligible in deriving the distanceto the subject using a histogram. In this way, in a case where ameasurement error occurs, the main control unit 26 may not store thecaptured image in the storage unit 48. In this case, the user can setwhether or not to store the captured image through the operating unit 44(an example of a storage setting unit according to the technique of thepresent disclosure).

Next, in Step 220, the distance measurement control unit 24 determineswhether or not a predetermined number of measurements end. In a casewhere a predetermined number of measurements do not end, the processreturns to Step 208, and the measurement is repeated. In a case where apredetermined number of measurements end, the process progresses to Step222.

In Step 222, the distance to the subject is derived based on the timefrom when the photodiode 36 emits the laser beam through the processingof Step 216 until the photodiode 36 receives the laser beam. As anexample, as shown in FIG. 4, the distance measurement control unit 24generates a histogram of the distance to the subject and derives thedistance to the subject corresponding to a maximum value of themeasurement frequency from the histogram as a measurement result. In acase where a histogram relating to the time, such as the reciprocationtime of the laser beam, is generated, first, the time corresponding tothe maximum value of the measurement frequency may be derived, and thedistance to the subject may be derived based on the derived time. Forexample, in a case of a histogram relating to the reciprocation time ofthe laser beam, the distance to the subject may be derived by ½ of thereciprocation time of the laser beam corresponding to the maximum valueof the measurement frequency×the light speed.

Next, in Step 224, the distance measurement control unit 24 transmitsdistance data indicating the distance derived in Step 222 to the maincontrol unit 26, and then, the process progresses to Step 226.

In Step 226, the distance measurement control unit 24 determines whetheror not to end this distance measurement processing. In a case where endconditions determined in advance are satisfied, for example, in a casewhere the main control unit 26 determines that the power switch isturned off, this distance measurement processing ends. In a case wherethe end conditions are not satisfied, the process returns to Step 200,and this distance measurement processing is repeated.

As described above, in the distance measurement device 10 of thisembodiment, in a case of performing the imaging operation and thedistance measurement operation in parallel, the main control unit 26performs control such that shake correction is not performed. In a caseof performing only the imaging operation, control is performed such thatshake correction is performed.

In this way, since the main control unit 26 of the distance measurementdevice 10 of this embodiment does not perform shake correction duringthe distance measurement, the central position of the image formed onthe imaging element 42 is not deviated from the irradiation position ofthe laser beam emitted by the laser diode 32. Therefore, according tothe distance measurement device 10 of this embodiment, it is possible tosuppress degradation of distance measurement accuracy due to shakecorrection.

In this embodiment, although a case where, in a case of performing theimaging operation and the distance measurement operation in parallel,the main control unit 26 performs control such that shake correction isnot performed has been described, the invention is not limited thereto,and a shake correction amount may be smaller than that in a case ofperforming normal imaging. A flowchart illustrating control processingin this case is shown in FIG. 8. In the control processing in this case,Step 103 may be provided instead of Step 104 of the control processingshown in FIG. 5, and Step 137 may be provided instead of Step 136. InFIG. 8, subsequent processing is the same as in the control processingshown in FIG. 5, and thus, description thereof will not be repeated.

In the control processing shown in FIG. 8, the main control unit 26progresses to Step 137 in a case of not performing the distancemeasurement, performs shake correction with a shake correction amount A,and then, progresses to Step 138 to perform normal imaging. The shakecorrection amount A is a shake correction amount in a case of performingnormal imaging, and is a correction amount for appropriately capturingan image of the subject.

The main control unit 26 progresses to Step 103 in a case of performingthe distance measurement, performs shake correction with a shakecorrection amount B, and then, progresses to Step 106 to perform theimaging operation in parallel with the distance measurement operation.The shake correction amount B is a correction amount smaller than theshake correction amount A. The correction amount B may be determinedaccording to degradation of distance measurement accuracy and imagequality of the captured image, and may be determined, for example, by anexperiment or the like in advance taking into consideration theinfluence on distance measurement accuracy.

In a case of performing shake correction during the distance measurementoperation, as described above, the irradiation position of the laserbeam moves. For this reason, the irradiation position may be displayedon the view finder 46. A flowchart illustrating control processing inthis case is shown in FIG. 9. In the control processing shown in FIG. 9,Step 105 is provided between Steps 103 and 106 of the control processingshown in FIG. 8. In a case of performing a main imaging operation andthe distance measurement operation in parallel, the main control unit 26sets the shake correction amount to the shake correction amount B, andthen, in Step 105, displays a marker representing the irradiationposition on a live view image displayed on the view finder 46 in asuperimposed manner. FIGS. 10A to 10C show a display example of a marker90. As shown in FIG. 10A, the marker 90 is displayed on a live viewimage displayed on the view finder 46 in a superimposed manner. The sizeof the marker 90 may be different depending on a shake amount. The maincontrol unit 26 computes a shake amount based on a detection result ofthe shake detection unit 43, in a case where the shake amount is large,as shown in FIG. 10B, displays the marker 90 large, and in a case wherethe shake amount is small, as shown in FIG. 10C, displays the marker 90small.

In this embodiment, although an imaging operation in a case of capturinga still image has been described, even in a case of capturing a motionimage, as in this embodiment, the main control unit 26 may control shakecorrection. In a case of displaying a live view image, and in a case ofperforming shake correction, as in this embodiment, the main controlunit 26 may control shake correction regardless of the imagingoperation.

In this embodiment, although the distance measurement control unit 24performs control such that the laser diode 32 emits light in thehorizontal blanking period, a timing at which the laser diode 32 emitslight may be a period during which the degree of influence on thereading state of the image signal is equal to or less than an allowabledegree determined in advance. When the degree of influence is theallowable degree determined in advance, for example, there is a casewhere image disruption to the extent of causing no problem (beingunnoticeable) in a case where the user visually recognizes the capturedimage is set within an allowable range, or the like. The laser diode 32may emit light in a period (a so-called vertical blanking period or thelike) during which the charges are not read between the frames inreading the charges, not in the horizontal blanking period.

As a method of synchronizing the distance measurement operation by thedistance measurement control unit 24 with the imaging operation by themain control unit 26, a clock signal of the time counter 22 may becontrolled using the main control unit 26.

In this embodiment, although an example where the distance measurementcontrol unit 24 derives the distance to the subject by performing ameasurement using the emission and reception of the laser beam multipletimes (for example, several 100 times) has been described, a focusadjustment result may be used when deriving the distance. For example,when analyzing the histogram (FIG. 4) generated from a plurality ofmeasurement results using the emission and reception of the laser beam,the distance range (the range of the subject distance and the vicinitythereof) of the distance to the subject is understood from the AFresult. Accordingly, as shown in FIG. 11A, the distance to the subjectmay be derived only using the measurement results within the subjectdistance range based on AF without using the measurement results(hatched portions in FIG. 11A) outside the subject distance range basedon AF. With this, if the distance range is determined, since aresolution is uniquely determined, it is possible to increase theresolution of the distance range when determining the frequency comparedto using all measured values, and to derive the distance to the subjectin units of minute numerical values. In the example of FIG. 11A,although an example in which the measured values of the distancesshorter and the distances longer than the subject distance range basedon AF are not used together has been shown, either of them may not beused. That is, the distance to the subject may be derived without usingthe measured values (a hatched portion in FIG. 11B) of the distancesless than the subject distance based on AF or the measured values (ahatched portion in FIG. 11C) of the distances longer than the subjectdistance based on AF. Furthermore, a result of manual focus adjustmentin the manual focus mode may be used instead of AF.

In this embodiment, in a case where the distance measurement controlunit 24 performs the distance measurement, as shown in FIG. 12, thefocusing state specification information specifying the AF result (orthe manual focus adjustment result) or the exposure state specificationinformation specifying the AE result is acquired from the main controlunit 26, and at least one of the laser diode 32 or the photodiode 36 maybe driven and adjusted based on the acquired focusing statespecification information and exposure state specification information.That is, since an approximate distance to the subject is understood fromthe focus adjustment result (focal distance), the emission intensity ofthe laser beam emitted from the laser diode 32 may be adjusted based onthe focusing state specification information specifying the AF result.For example, the shorter the focal distance, the lower the emissionintensity is set. With this, while ambient light becomes noise, it ispossible to derive the distance to the subject with proper emissionintensity of the laser beam without being affected by noise of ambientlight. Similarly, since an approximate distance to the subject isunderstood from the focus adjustment result, the light receivingsensitivity of the photodiode 36 may be adjusted based on the focusingstate specification information specifying the AF result. For example,the shorter the focal distance, the lower the light receivingsensitivity is set. With this, it is possible to derive the distance tothe subject with proper light receiving sensitivity without beingaffected by noise of ambient light. Alternatively, since necessaryintensity of the laser beam is understood from the exposure adjustmentresult, the emission intensity of the laser beam may be adjusted basedon the exposure state specification information specifying the AEresult. For example, the higher the exposure, the lower the emissionintensity is set. Alternatively, since high exposure means that subjectbrightness becomes low, the lower the subject brightness, the lower theemission intensity may be set. With this, it is possible to derive thedistance to the subject with proper emission intensity of the laser beamwithout being affected by noise of ambient light.

In this embodiment, although a case where the distance measurementdevice 10 captures a still image has been described, even in a case ofcapturing a motion image, the main control unit 26 may perform controlas described above. In capturing a motion image, a measurement(measurement sequence) may be repeatedly performed. Furthermore, a stillimage may be repeatedly captured during a single measurement.

In this embodiment, although a case where voltage adjustment isperformed simultaneously with the distance measurement start timing andthe actual exposure start timing has been illustrated, the technique ofthe present disclosure is not limited thereto. For example, as shown inFIG. 13, prior to the start of the distance measurement and the start ofthe actual exposure, as a specific example, the voltage adjustment maybe performed in a period during which a live view image is displayed, orthe like. In this case, for example, in the distance measurementprocessing by the distance measurement control unit 24 shown in FIG. 7,the processing of Steps 202 and 204 may be performed prior to Step 200.Furthermore, the voltage adjustment may not be performed.

In the above-described embodiment, although a case where informationrelating to the distance to the subject is displayed on the view finder46 so as to be superimposed on a live view image has been illustrated,the technique of the present disclosure is not limited thereto. Forexample, information relating to the distance to the subject may bedisplayed in a display area different from the display area of the liveview image. In this way, information relating to the distance to thesubject may be displayed on the view finder 46 in parallel with thedisplay of the live view image.

In the above-described embodiment, for convenience of description,although description has been provided on an assumption that there is noAF error, the technique of the present disclosure is not limitedthereto. That is, the distance measurement control unit 24 may derivethe distance as described above in a case where an AF error does notoccur, and may not derive the distance in a case where an AF erroroccurs.

In the above-described embodiment, for convenience of description,although description has been provided on an assumption that there is noAE error, the technique of the present disclosure is not limitedthereto. That is, the distance measurement control unit 24 may derivethe distance as described above in a case where an AE error does notoccur, and may not derive the distance in a case where an AE erroroccurs.

In the above-described embodiment, although the focus adjustment and theexposure adjustment by AF and AE have been illustrated, the technique ofthe present disclosure is not limited thereto, focus adjustment bymanual focus and exposure adjustment by manual exposure may be applied.

In the above-described embodiment, although a case where the releasebutton provided in the distance measurement device 10 is operated hasbeen illustrated, the technique of the present disclosure is not limitedthereto. For example, AE and AF may be started in response to an imagingpreparation instruction received by a user interface (UI) unit of anexternal device used in the form of being connected to the distancemeasurement device 10, and actual exposure may be started in response toan imaging instructed received by the UI unit of the external device.Examples of the external device used in the form of being connected tothe distance measurement device 10 include a smart device, a personalcomputer (PC), or a spectacles type or a wristwatch type wearableterminal device.

In the above-described embodiment, although a case where the live viewimage and the distance measurement result (information relating to thedistance to the subject) are displayed on the view finder 46 has beenillustrated, the technique of the present disclosure is not limitedthereto. For example, at least one of the live view image or thedistance measurement result may be displayed on a display unit of theexternal device used in the form of being connected to the distancemeasurement device 10. Examples of the display unit of the externaldevice used in the form of being connected to the distance measurementdevice 10 include a display of a smart device, a display of a PC, or adisplay of a wearable terminal device.

The control processing (see FIG. 5) and the distance measurementprocessing (see FIGS. 5A and 5B) described in the above-describedembodiment are merely examples. Accordingly, it is needless to say thatunnecessary steps may be deleted, new steps may be added, or theprocessing order may be rearranged without departing the gist of theinvention. The respective processing included in the control processingand the distance measurement processing described in the above-describedembodiment may be realized by a software configuration using a computerby executing a program, or may be realized by other hardwareconfigurations. Furthermore, the respective processing may be realizedby a combination of a hardware configuration and a softwareconfiguration.

Furthermore, it is needless to say that the technique of the presentdisclosure can also be applied to a digital camera.

In the above-described embodiment, although a case where the lightemission frequency of the laser beam is fixed has been illustrated, thetechnique of the present disclosure is not limited thereto. Sinceambient light becomes noise for the laser beam, the light emissionfrequency of the laser beam may be a light emission frequency determinedaccording to subject brightness.

Hereinafter, an example of a way of determining the light emissionfrequency of the laser beam will be described.

The light emission frequency of the laser beam is derived from a lightemission frequency determination table 300 shown in FIG. 14 as anexample. In the light emission frequency determination table 300, thesubject brightness and the light emission frequency of the laser beamare correlated with each other such that the higher the subjectbrightness, the larger the light emission frequency of the laser beambecomes. That is, in the light emission frequency determination table300, the subject brightness has a magnitude relationship of L₁<L₂< . . .<L_(n), and the light emission frequency has a magnitude relationship ofN₁<N₂< . . . <N_(n). In the example shown in FIG. 2, although the lightemission frequency in units of 100 times has been illustrated, theinvention is not limited thereto, and the light emission frequency maybe determined in units of ten times or once by the light emissionfrequency determination table 300.

In the distance measurement device 10, in order to realize thederivation of the light emission frequency of the laser beam by thelight emission frequency determination table 300, brightness informationtransmission processing (see FIG. 15) is executed by the main controlunit 26, and light emission frequency determination processing (see FIG.16) is executed by the distance measurement control unit 24.

First, the brightness information transmission processing which isexecuted by the main control unit 26 if the power switch of the distancemeasurement device 10 is turned on will be described referring to FIG.15.

In the brightness information transmission processing shown in FIG. 15,first, in Step 400, the main control unit 26 determines whether or notbrightness acquisition start conditions which are conditions forstarting acquisition of subject brightness are satisfied. An example ofthe brightness acquisition start conditions is a condition that therelease button is half-pressed. Another example of the brightnessacquisition start conditions is a condition that the captured image isoutput from the imaging element 42.

In Step 400, in a case where the brightness acquisition start conditionsare satisfied, the determination is affirmative, and the processprogresses to Step 402. In Step 400, in a case where the brightnessacquisition start conditions are not satisfied, the determination isnegative, and the process progresses to Step 406.

In Step 402, the main control unit 26 acquires the subject brightnessfrom the captured image, and then, the process progresses to Step 404.Here, although a case where the subject brightness is acquired from thecaptured image has been illustrated, the technique of the presentdisclosure is not limited thereto. For example, if a brightness sensorwhich detects subject brightness is mounted in the distance measurementdevice 10, the main control unit 26 may acquire the subject brightnessfrom the brightness sensor.

In Step 404, the main control unit 26 transmits brightness informationindicating the subject brightness acquired in Step 402 to the distancemeasurement control unit 24, and then, the process progresses to Step406.

In Step 406, the main control unit 26 determines whether or not endconditions which are conditions for ending this brightness informationtransmission processing are satisfied. An example of the end conditionsis a condition that the power switch of the distance measurement device10 is turned off. In Step 406, in a case where the end conditions arenot satisfied, the determination is negative, and the process progressesto Step 400. In Step 406, in a case where the end conditions aresatisfied, the determination is affirmative, and this brightnessinformation transmission processing ends.

Next, the light emission frequency determination processing which isexecuted by the distance measurement control unit 24 if the power switchof the distance measurement device 10 is turned on will be describedreferring to FIG. 16.

In the light emission frequency determination processing shown in FIG.16, first, in Step 410, the distance measurement control unit 24determines whether or not the brightness information transmitted byexecuting the processing of Step 404 is received. In Step 410, in a casewhere the brightness information transmitted by executing the processingof Step 404 is not received, the determination is negative, and theprocess progresses to Step 416. In Step 410, in a case where thebrightness information transmitted by executing the processing of Step404 is received, the determination is affirmative, and the processprogresses to Step 412.

In Step 412, the distance measurement control unit 24 derives the lightemission frequency corresponding to the subject brightness indicated bythe brightness information received in Step 410 from the light emissionfrequency determination table 300, and then, the process progresses toStep 414.

In Step 414, the distance measurement control unit 24 stores the lightemission frequency derived in the processing of Step 412 in the storageunit 48, and then, the process progresses to Step 416. The lightemission frequency stored in the storage unit 48 by the processing ofStep 416 means “a predetermined number of times” in Step 220 of thedistance measurement processing shown in FIG. 7.

In Step 416, the main control unit 26 determines whether or not endconditions which are conditions for ending this light emission frequencydetermination processing are satisfied. An example of the end conditionsis a condition that the power switch of the distance measurement device10 is turned off. In Step 416, in a case where the end conditions arenot satisfied, the determination is negative, and the process progressesto Step 410. In Step 416, in a case where the end conditions aresatisfied, the determination is affirmative, and this light emissionfrequency determination processing ends.

Next, another example of a way of determining the light emissionfrequency of the laser beam will be described.

As an example, the light emission frequency of the laser beam is derivedaccording to a light emission frequency determination table 500 shown inFIG. 17. In the light emission frequency determination table 500,exposure state specification information (E₁, E₂, . . . , E_(n))uniquely determined according to the subject brightness and the lightemission frequency (N₁, N₂, . . . , N_(n)) of the laser beam arecorrelated with each other. Here, the exposure state specificationinformation uniquely determined according to the subject brightnessmeans, for example, exposure state specification information indicatingthat, the higher the subject brightness, the lower the exposure becomes.

In a case of deriving the light emission frequency of the laser beamusing the light emission frequency determination table 500, exposurestate specification information transmission processing (see FIG. 18) isexecuted by the main control unit 26, and light emission frequencydetermination processing (see FIG. 19) is executed by the distancemeasurement control unit 24.

First, the exposure state specification information transmissionprocessing which is executed by the main control unit 26 if the powerswitch of the distance measurement device 10 is turned on will bedescribed referring to FIG. 18.

In the exposure state specification information transmission processingshown in FIG. 18, first, in Step 600, the main control unit 26determines whether or not the release button is half-pressed. In Step600, in a case where the release button is not half-pressed, thedetermination is negative, and the process progresses to Step 606. InStep 600, in a case where the release button is half-pressed, thedetermination is affirmative, and the process progresses to Step 602. InFIG. 18, although a case where the operating unit 44 comprises therelease button has been described as an example, the technique of thepresent disclosure is not limited thereto. For example, in a case wherethe operating unit 44 comprises a distance measurement imaging startbutton, Step 600 may be omitted, and in a case where power is supplied,the processing of Step 602 may be started.

In Step 602, the main control unit 26 performs AE based on the subjectbrightness acquired from the captured image, and then, the processprogresses to Step 604.

In Step 604, the main control unit 26 transmits the exposure statespecification information to the distance measurement control unit 24,and then, the process progresses to Step 606.

In Step 606, the main control unit 26 determines whether or not endconditions which are conditions for ending this exposure statespecification information transmission processing are satisfied. Anexample of the end conditions is a condition that the power switch ofthe distance measurement device 10 is turned off. In Step 606, in a casewhere the end conditions are not satisfied, the determination isnegative, and the process progresses to Step 600. In Step 606, in a casewhere the end conditions are satisfied, the determination isaffirmative, and this exposure state specification informationtransmission processing ends.

Next, the light emission frequency determination processing which isexecuted by the distance measurement control unit 24 if the power switchof the distance measurement device 10 is turned on will be describedreferring to FIG. 19.

In the light emission frequency determination processing shown in FIG.19, first, in Step 610, the distance measurement control unit 24determines whether or not the exposure state specification informationtransmitted by executing the processing of Step 604 is received. In Step610, in a case where the exposure state specification informationtransmitted by executing the processing of Step 604 is not received, thedetermination is negative, and the process progresses to Step 616. InStep 610, in a case where the exposure state specification informationtransmitted by the executing the processing of Step 604 is received, thedetermination is affirmative, and the process progresses to Step 612.

In Step 612, the distance measurement control unit 24 derives the lightemission frequency corresponding to the exposure state specificationinformation received in Step 610 from the light emission frequencydetermination table 500, and then, the process progresses to Step 614.

In Step 614, the distance measurement control unit 24 stores the lightemission frequency derived in the processing of Step 612 in the storageunit 48, and then, the process progresses to Step 616. The lightemission frequency stored in the storage unit 48 by the processing ofStep 616 means “a predetermined number of times” in Step 220 of thedistance measurement processing shown in FIG. 7.

In Step 616, the main control unit 26 determines whether or not endconditions which are conditions for ending this exposure statespecification information transmission processing are satisfied. Anexample of the end conditions is a condition that the power switch ofthe distance measurement device 10 is turned off. In Step 616, in a casewhere the end conditions are not satisfied, the determination isnegative, and the process progresses to Step 610. In Step 616, in a casewhere the end conditions are satisfied, the determination isaffirmative, and this exposure state specification informationtransmission processing ends.

In this way, since the distance measurement device 10 makes the lightemission frequency (distance measurement frequency) of the laser beamlarger when the subject brightness is higher, it is possible to obtain adistance measurement result, in which the influence of noise of ambientlight is moderated, compared to a case where the light emissionfrequency (distance measurement frequency) of the laser beam is fixedregardless of the subject brightness.

In the above-described embodiment, although the laser beam has beenillustrated as light for distance measurement, the technique of thepresent disclosure is not limited thereto, and directional light whichis light having directivity may be used. For example, directional lightwhich is obtained by a light emitting diode (LED) or a super luminescentdiode (SLD) may be used. The directivity of directional light ispreferably the same directivity as the directivity of the laser beam,and is preferably, for example, the directivity usable in a distancemeasurement within a range of several meters to several kilometers.

The disclosures of Japanese Patent Application No. 2014-095556 filed onMay 2, 2014 and Japanese Patent Application No. 2014-159806 filed onAug. 5, 2014 are incorporated by reference in this specification.

All documents, patent applications, and technical specificationsdescribed in this specification are incorporated by reference in thisspecification as if each of the documents, the patent applications, andthe technical specification is concretely and respectively specified asbeing incorporated by reference herein.

In regard to the above embodiment, the following appendixes are furtherdisclosed.

APPENDIX 1

A distance measurement device comprising an imaging optical system whichforms a subject image indicating a subject, an imaging unit whichcaptures the subject image formed by the imaging optical system, anemission unit which emits a laser beam along an optical axis directionof the imaging optical system, a light receiving unit which receivesreflected light of the laser beam from the subject, a derivation unitwhich performs a distance measurement to derive a distance to thesubject based on a timing at which the laser beam is emitted by theemission unit and a timing at which the reflected light is received bythe light receiving unit, a camera shake correction unit which performscamera shake correction, and a control unit which performs control suchthat the camera shake correction unit does not perform the camera shakecorrection or performs the camera shake correction with a correctionamount smaller than a normal correction amount determined in advance ina case of performing the distance measurement and performs the camerashake correction with the normal correction amount in a case of notperforming the distance measurement.

APPENDIX 2

A distance measurement method comprising performing a distancemeasurement to derive a distance to a subject based on a timing at whicha laser beam is emitted by an emission unit emitting the laser beamalong an optical axis direction of an imaging optical system forming asubject image indicating the subject and a timing at which reflectedlight is received by a light receiving unit receiving the reflectedlight of the laser beam from the subject, and performing control suchthat a camera shake correction unit does not perform camera shakecorrection or performs the camera shake correction with a correctionamount smaller than a normal correction amount determined in advance ina case of performing the distance measurement and performs the camerashake correction with the normal correction amount in a case of notperforming the distance measurement.

APPENDIX 3

A distance measurement program which causes a computer to executeprocessing including performing a distance measurement to derive adistance to a subject based on a timing at which a laser beam is emittedby an emission unit emitting the laser beam along an optical axisdirection of an imaging optical system forming a subject imageindicating the subject and a timing at which reflected light is receivedby a light receiving unit receiving the reflected light of the laserbeam from the subject, and performing control such that a camera shakecorrection unit does not perform camera shake correction or performs thecamera shake correction with a correction amount smaller than a normalcorrection amount determined in advance in a case of performing thedistance measurement and performs the camera shake correction with thenormal correction amount in a case of not performing the distancemeasurement.

What is claimed is:
 1. A digital camera comprising: an imaging opticalsystem which forms a subject image indicating a subject; an image sensorwhich captures the subject image formed by the imaging optical systemand an electronic shutter function in an imaging operation; an emitterwhich emits directional light as light having directivity along anoptical axis direction of the imaging optical system; a light receiverwhich receives reflected light of the directional light from thesubject; the light receiver being used for derivation of a distance tothe subject based on a timing at which the directional light is emittedby the emitter and a timing at which the reflected light is received bythe light receiver in a distance measurement operation; a shakecorrection mechanism which performs shake correction as correction ofshake of the subject image caused by variation of the optical axis ofthe imaging optical system; and a processor configured to receive a userinstruction of capturing the subject image, wherein in a case in whichthe processor receives the user instruction, the processor performs thedistance measurement operation and the imaging operation using theelectronic shutter function and the shake correction mechanism, andwherein the distance measurement operation and the imaging operation aresynchronized so that the emitter emits the directional light in ahorizontal blanking period or vertical blanking period of the imagesensor.
 2. The digital camera according to claim 1 further comprising: aderivation circuit which performs a derivation of distance multipletimes and derives a distance having a high frequency among the distancesobtained by deriving the distance multiple times as a final distance onthe distance measurement operation.
 3. The digital camera according toclaim 2, wherein, in a case where the processor executes a focusadjustment, and in a case of deriving the distance, the derivationcircuit determines a distance range for use when determining thefrequency or a time range from the emission of the directional light tothe reception of the directional light based on focusing statespecification information and derives the final distance within thedetermined distance range or the determined time range.
 4. The digitalcamera according to claim 3, wherein, in a case of deriving thedistance, the derivation circuit derives the final distance with aresolution determined according to a result of determination of thedistance range or the time range.
 5. The digital camera according toclaim 1, wherein drive of the emitter or the light receiver is adjustedaccording to information of an exposure state of an imaging condition.6. The digital camera according to claim 1, wherein when a secondexposure state is of a higher exposure than a first exposure state, anemission intensity of the emitter in the second exposure state is setlower than an emission intensity of the emitter in the first exposurestate.
 7. The digital camera according to claim 1, wherein drive of theemitter or the light receiver is adjusted according to a distance fromthe digital camera to the subject.
 8. The digital camera according toclaim 1, wherein when a first distance from the digital camera to thesubject is shorter than a second distance from the digital camera to thesubject, an emission intensity of the emitter is set lower on the firstdistance than an emission intensity of the emitter on the seconddistance.
 9. The digital camera according to claim 1, wherein theprocessor is configured to receive a user instruction regarding whethershake correction is performed or not.
 10. The digital camera accordingto claim 1, wherein the distance measurement operation is performed anumber of times determined according to subject brightness or exposurestate specification information.
 11. The digital camera according toclaim 1, wherein the distance measurement operation is performed anincreased number of times when the subject brightness increases or whenthe exposure indicated by the exposure state specification informationdecreases.
 12. The digital camera according to claim 1, wherein, in acase in which the processor performs the imaging operation with thedistance measurement operation, the processor sets the shake correctionamount to be smaller than in a case in which the processor performs theimaging operation without the distance measurement operation, or theprocessor controls the shake correction mechanism so as to not performthe shake correction.
 13. The digital camera according to claim 12,wherein, in a case in which the processor performs the imaging operationwithout the distance measurement operation, the processor controls theshake correction mechanism so as to perform the shake correction in theimaging operation.
 14. The digital camera according to claim 9, wherein,in a case in which the processor performs the imaging operation with thedistance measurement operation, the processor sets the shake correctionamount to be smaller than in a case in which the processor performs theimaging operation without the distance measurement operation, or theprocessor controls the shake correction mechanism so as to not performthe shake correction.
 15. The digital camera according to claim 14,wherein, in a case in which the processor performs the imaging operationwithout the distance measurement operation, the processor controls theshake correction mechanism so as to perform the shake correction in theimaging operation.
 16. A digital camera comprising: an imaging opticalsystem which forms a subject image indicating a subject; an image sensorwhich captures the subject image formed by the imaging optical systemand an electronic shutter function in an imaging operation; an emitterwhich emits directional light as light having directivity along anoptical axis direction of the imaging optical system; a light receiverwhich receives reflected light of the directional light from thesubject; the light receiver being used for derivation of a distance tothe subject based on a timing at which the directional light is emittedby the emitter and a timing at which the reflected light is received bythe light receiver in a distance measurement operation; a shakecorrection mechanism which performs shake correction as correction ofshake of the subject image caused by variation of the optical axis ofthe imaging optical system; and a processor configured to receive a userinstruction of capturing the subject image, wherein in a case in whichthe processor receives the user instruction, the processor performs thedistance measurement operation and the imaging operation using theelectronic shutter function and the shake correction mechanism, andwherein the distance measurement operation is performed a number oftimes determined according to subject brightness or exposure statespecification information.
 17. A digital camera comprising: an imagingoptical system which forms a subject image indicating a subject; animage sensor which captures the subject image formed by the imagingoptical system and an electronic shutter function in an imagingoperation; an emitter which emits directional light as light havingdirectivity along an optical axis direction of the imaging opticalsystem; a light receiver which receives reflected light of thedirectional light from the subject; the light receiver being used forderivation of a distance to the subject based on a timing at which thedirectional light is emitted by the emitter and a timing at which thereflected light is received by the light receiver in a distancemeasurement operation; a shake correction mechanism which performs shakecorrection as correction of shake of the subject image caused byvariation of the optical axis of the imaging optical system; and aprocessor configured to receive a user instruction of capturing thesubject image, wherein in a case in which the processor receives theuser instruction, the processor performs the distance measurementoperation and the imaging operation using the electronic shutterfunction and the shake correction mechanism, and wherein the distancemeasurement operation is performed an increased number of times when thesubject brightness increases or when the exposure indicated by theexposure state specification information decreases.